The Granzyme B Assay Kit for Drug Discovery is a complete assay system designed to measure the protease activity of granzyme B. It contains a colorimetric substrate (IEPD-pNA) to measure this activity; cleavage of the p-nitroanilide (pNA) group from the colorimetric substrate increases absorption at 405 nm.

The kit is useful to screen for inhibitors of granzyme B, a potential therapeutic target. An inhibitor 3, 4-Dichloroisocoumarin, is also included for use as a control.

Granzyme B is a serine protease found in the lymphocyte granules of cytotoxic T-lymphocytes (CTLs) and natural killer (NK) cells. Granzyme B plays a crucial role in the development of acute graft-vs.-host disease. Thus, the inhibition of this enzyme may prove to be an important tool in controlling immune responses.